1. Field of the Invention
This invention generally relates to methods and solutions for processing a microelectronic topography and, more specifically, to methods for preventing precipitation of etch byproducts onto a microelectronic topography during an etch process and/or a subsequent rinse process.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
The fabrication of microelectronic topographies generally includes a plurality of processing steps including but not limited to depositing, patterning, and etching materials to form a compilation of device structures. In some embodiments, conductive structures may be formed within a sacrificial layer of a microelectronic topography and then portions or all of the sacrificial layer may be subsequently removed, exposing the sidewalls of the conductive structures. Thereafter, the microelectronic topography may be rinsed with deionized water to remove the etching solution and/or byproducts and subsequently dried. In some cases, the etching, rinsing, and/or drying processes may cause the conductive structures to collapse (i.e., topple towards each other) rendering the microelectronic topography unusable. The occurrence of feature collapse appears to be increasing, particularly as width dimensions of structures continue to decrease and resulting aspect ratios increase with the ever pressing goal to increase processing speed and memory density of integrated circuits. In particular, it appears that the aspect ratios of conductive structures may, in some embodiments, be increased to an extent that surface tension of liquids between the conductive structures causes the conductive structures to collapse.
One technique which has been shown to mitigate feature collapse is to etch a sacrificial layer in an environment of a supercritical fluid and subsequently vent the etch chamber such that the formation of a liquid on the topography is prevented. In general, supercritical fluids are void of surface tension. As such, generally no fluids bearing surface tension are placed between device structures of a topography during such a process. Consequently, feature collapse may be abated. A disadvantage of etching in an environment of a supercritical fluid, however, is that etch byproducts generated during the etch process tend to have low solubility in the supercritical fluid and may be susceptible to precipitating onto the topography. In some cases, precipitates of etch byproducts may undesirably alter and, in some embodiments, detrimentally affect the functionality of an ensuing device. For example, precipitates of dissolved oxide may, in some cases, increase contact resistance on conductive device structures. As such, a process for removing precipitant material may be desired after an etch process which is prone to produce precipitant material. However, in order to remove material precipitated upon a topography, a wet rinse is typically needed. As noted above, employing wet processes on a microelectronic topography having device structures may lead to feature collapse due to the surface tension of the fluids.
It would, therefore, be advantageous to develop methods for preventing precipitation of etch byproducts onto a topography during and subsequent to etching portions of the topography in an environment of a supercritical fluid.